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Báo cáo hóa học: " Research Article Employing LSF at Transmitter Eases MMSE Adaptation at Receiver in Asynchronous CDMA Systems"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Employing LSF at Transmitter Eases MMSE Adaptation at Receiver in Asynchronous CDMA Systems | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2008 Article ID 298784 9 pages doi 10.1155 2008 298784 Research Article Employing LSF at Transmitter Eases MMSE Adaptation at Receiver in Asynchronous CDMA Systems Masahiro Yukawa 1 Ken Umeno 2 and Gen Hori2 1 Amari Research Unit BSI 2-1 Hirosawa Wako Saitama 351-0198 Japan 2 Next Generation Mobile Communications Laboratory CIPS 2-1 Hirosawa Wako Saitama 351-0106 Japan Correspondence should be addressed to Masahiro Yukawa myukawa@riken.jp Received 22 July 2008 Accepted 11 December 2008 Recommended by Chi Ko The Lebesgue spectrum filter LSF a finite impulse response FIR filter whose coefficients decay exponentially with a negative factor r V3 - 2 is shown to be effective preprocessing for spreading code in asynchronous code-division multiple-access CDMA systems. The LSF has only been studied independently from the well-known minimum mean-square error MMSE filter an optimal FIR filter in the mean-square error sense. In this paper we propose an efficient structure employing the LSF at the transmitter and the MMSE filter at the receiver for asynchronous CDMA systems. We employ a spreading code preprocessed by the LSF referred to as LSF-code and the LSF-code supplies a best initial estimate among the ones obtained without any a priori information to an adaptive algorithm for the MMSE filter leading to significant reduction of iterations in adaptation. This is verified by computer simulations. Also we investigate the link between the LSF and the MMSE filter by examining their autocorrelation properties. Copyright 2008 Masahiro Yukawa et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION We study two kinds of finite impulse response FIR filters optimal in different senses for an asynchronous direct .